Tadalafil is its active ingredient and is available as a generic drug. Brand-name versions of the drug approved for PAH include Adcirca. When the smaller blood vessels in the lungs become more resistant to blood flow, the right ventricle must work harder to pump enough blood through the lungs. Tadalafil belongs to a group of medicines called phosphodiesterase 5 PDE5 inhibitors. Erectile dysfunction is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection. When a man is sexually stimulated, his body’s normal response is to increase blood flow to his penis to produce an erection. What Is Cialis?Brand-name Cialis: $20 – $80 per dose (5mg, 10mg, 20mg) Generic Cialis (tadalafil): $11 – $44 per dose (5mg, 10mg, 20mg) Daily generic Cialis (tadalafil): $8 per .  · Cialis tablets come in four strengths: milligrams (mg), 5 mg, 10 mg, and 20 mg. What are the typical dosages of Cialis? Typically, your doctor will start you on a .  · Description and Brand Names Drug information provided by: Merative, Micromedex ® US Brand Name Adcirca Cialis Descriptions Tadalafil is used to treat .